The GETUG 70 Gy vs. 80 Gy randomized trial for localized prostate cancer: feasibility and acute toxicity

Abstract

Purpose: To describe treatments and acute tolerance in a randomized trial comparing 70 Gy and 80 Gy to the prostate in patients with localized prostate cancer.

Methods and materials: Between September 1999 and February 2002, 306 patients were randomized to receive 70 Gy (153 patients) or 80 Gy (153 patients) in 17 institutions. Patients exhibited intermediate-prognosis tumors. If the risk of node involvement was greater than 10%, surgical staging was required. Previous prostatectomy was excluded, and androgen deprivation was not admitted. The treatment was delivered in two steps. PTV1-including seminal vesicles, prostate, and a 1-0.5-cm margin-received 46 Gy given with a 4-field conformal technique. PTV2, reduced to prostate with the same margins, irradiated with at least 5 fields. Dose was prescribed according to ICRU recommendations in the 70 Gy group, but adapted at the 80 Gy level.

Results: All patients but one in the 80 Gy arm completed the treatment. In the 70 Gy arm, the mean dose to the PTV2 was 69.5 Gy. In the 80 Gy arm, the mean dose in the PTV2 was 78.5 Gy. Acute toxicity according to Radiation Therapy Oncology Group scale during treatment was reported in 306 patients. There was no statistically significant difference between the two arms: 12% had no toxicity, 80% complained of bladder toxicity, and 70% complained of rectal symptoms. Two months after the end of treatment, 43% of the 70 Gy level and 48% of the 80 Gy level complained of side effects, including 24% and 20% of sexual disorders. There was 6% and 2% of Grade 3 urinary and rectal toxicity. Five patients required a 10-29-day suspension of the treatment. Acute Grade 2 and 3 side effects were related to PTV and CTV1 size, which was the only independent predictive factor in multivariate analysis. Toxicity was not related to the center, age, arm of treatment, or selected data from dose-volume histogram of organ at risk.

Conclusion: Treatments were completed in respect to constraints. Acute toxicity was acceptable. Intensity of toxicity depended on target volumes.